Articles | Volume 2, issue 1
https://doi.org/10.5194/mr-2-33-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/mr-2-33-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Room-temperature hyperpolarization of polycrystalline samples with optically polarized triplet electrons: pentacene or nitrogen-vacancy center in diamond?
Koichiro Miyanishi
CORRESPONDING AUTHOR
Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-Ku, Kyoto 615-8510, Japan
Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
Kazuyuki Takeda
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
Izuru Ohki
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Shinobu Onoda
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
Takeshi Ohshima
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
Hiroshi Abe
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
Hideaki Takashima
Department of Electronic Science and Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
Shigeki Takeuchi
Department of Electronic Science and Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
Alexander I. Shames
Department of Physics, Ben-Gurion University of the Negev, 8410501 Beer-Sheva, Israel
Kohki Morita
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Yu Wang
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
Frederick T.-K. So
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-Ku, Kyoto 615-8510, Japan
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Daiki Terada
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-Ku, Kyoto 615-8510, Japan
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Ryuji Igarashi
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
JST, PRESTO, Kawaguchi, Japan
Akinori Kagawa
Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
JST, PRESTO, Kawaguchi, Japan
Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-2 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
Masahiro Kitagawa
Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-2 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
Norikazu Mizuochi
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Masahiro Shirakawa
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-Ku, Kyoto 615-8510, Japan
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
Makoto Negoro
CORRESPONDING AUTHOR
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
JST, PRESTO, Kawaguchi, Japan
Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-2 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
Cited articles
Abrams, D., Trusheim, M. E., Englund, D. R., Shattuck, M. D., and Meriles,
C. A.: Dynamic nuclear spin polarization of liquids and gases in contact with
nanostructured diamond, Nano Lett., 14, 2471–2478, https://doi.org/10.1021/nl500147b,
2014. a
Acosta, V., Jarmola, A., Bauch, E., and Budker, D.: Optical properties of the
nitrogen-vacancy singlet levels in diamond, Phys. Rev. B, 82, 201202,
https://doi.org/10.1103/PhysRevB.82.201202, 2010. a
Ajoy, A., Liu, K., Nazaryan, R., Lv, X., Zangara, P. R., Safvati, B., Wang, G., Arnold, D., Li, G., Lin, A., Raghavan, P., Druga, E., Dhomkar, S., Pagliero, D., Reimer, J. A., Suter, D., Meriles, C. A., and Pines, A.:
Orientation-independent room temperature optical 13C hyperpolarization
in powdered diamond, Sci. Adv., 4, eaar5492, https://doi.org/10.1126/sciadv.aar5492,
2018a. a, b, c
Ajoy, A., Nazaryan, R., Liu, K., Lv, X., Safvati, B., Wang, G., Druga, E.,
Reimer, J. A., Suter, D., Ramanathan, C., Meriles, C. A., and Pines, A.:
Enhanced dynamic nuclear polarization via swept microwave frequency combs,
P. Natl. Acad. Sci. USA, 115, 10576–10581, https://doi.org/10.1073/pnas.1807125115, 2018b. a
Ajoy, A., Safvati, B., Nazaryan, R., Oon, J. T., Han, B., Raghavan, P., Nirodi, R., Aguilar, A., Liu, K., Cai, X., Lv, X., Druga, E., Ramanathan, C., Reimer, J. A., Meriles, C. A., Suter, D., and Pines, A.: Hyperpolarized relaxometry based nuclear T1 noise spectroscopy in diamond, Nat. Commun., 10, 5160, https://doi.org/10.1038/s41467-019-13042-3, 2019. a
Ajoy, A., Nazaryan, R., Druga, E., Liu, K., Aguilar, A., Han, B., Gierth, M.,
Oon, J. T., Safvati, B., Tsang, R., Walton, J. H., Suter, D., Meriles, C. A., Reimer, J. A., and Pines, A.: Room temperature “optical
nanodiamond hyperpolarizer”: Physics, design, and operation, Rev. Sci.
Instrum., 91, 023106, https://doi.org/10.1063/1.5131655, 2020. a
Álvarez, G. A., Bretschneider, C. O., Fischer, R., London, P., Kanda, H.,
Onoda, S., Isoya, J., Gershoni, D., and Frydman, L.: Local and bulk 13C
hyperpolarization in nitrogen-vacancy-centred diamonds at variable fields and
orientations, Nat. Commun., 6, 8456, https://doi.org/10.1038/ncomms9456, 2015. a
Ardenkjær-Larsen, J. H., Fridlund, B., Gram, A., Hansson, G., Hansson, L., Lerche, M. H., Servin, R., Thaning, M., and Golman, K.: Increase in
signal-to-noise ratio of > 10 000 times in liquid-state NMR, P. Natl. Acad. Sci. USA, 100, 10158–10163, https://doi.org/10.1073/pnas.1733835100,
2003. a
Awschalom, D. D. and Flatté, M. E.: Challenges for semiconductor
spintronics, Nat. Phys., 3, 153–159, https://doi.org/10.1038/nphys551, 2007. a
Can, T. V., Weber, R. T., Walish, J. J., Swager, T. M., and Griffin, R. G.:
Frequency-Swept Integrated Solid Effect, Angew. Chem. Int. Edit., 56,
6744–6748, https://doi.org/10.1021/acs.jpclett.8b01002, 2017. a
Casabianca, L. B., Shames, A. I., Panich, A. M., Shenderova, O., and Frydman,
L.: Factors affecting DNP NMR in polycrystalline diamond samples,
J. Phys. Chem. C, 115, 19041–19048, https://doi.org/10.1021/jp206167j, 2011. a
Chen, J., Lourette, S., Rezai, K., Hoelzer, T., Lake, M., Nesladek, M.,
Bouchard, L.-S., Hemmer, P., and Budker, D.: Optical quenching and recovery
of photoconductivity in single-crystal diamond, Appl. Phys. Lett., 110,
011108, https://doi.org/10.1063/1.4973692, 2017. a
Chen, Q., Schwarz, I., Jelezko, F., Retzker, A., and Plenio, M. B.: Optical
hyperpolarization of 13C nuclear spins in nanodiamond ensembles, Phys.
Rev. B, 92, 184420, https://doi.org/10.1103/PhysRevB.92.184420, 2015. a
Corval, A., Kryschi, C., Astilean, S., and Trommsdorff, H. P.: Resonant
intersystem crossing in pentacene, J. Phys. Chem., 98, 7376–7381,
https://doi.org/10.1021/j100081a024, 1994. a
Deimling, M., Brunner, H., Dinse, K., Hausser, K., and Colpa, J.:
Microwave-induced optical nuclear polarization (MI-ONP), J. Magn. Reson., 39, 185–202, https://doi.org/10.1016/0022-2364(80)90128-6, 1980. a
Doherty, M. W., Manson, N. B., Delaney, P., Jelezko, F., Wrachtrup, J., and
Hollenberg, L. C.: The nitrogen-vacancy colour centre in diamond, Phys. Rep.,
528, 1–45, https://doi.org/10.1016/j.physrep.2013.02.001, 2013. a, b
Fischer, R., Bretschneider, C. O., London, P., Budker, D., Gershoni, D., and
Frydman, L.: Bulk Nuclear Polarization Enhanced at Room Temperature by
Optical Pumping, Phys. Rev. Lett., 111, 057601,
https://doi.org/10.1103/PhysRevLett.111.057601, 2013. a
Gruber, A., Dräbenstedt, A., Tietz, C., Fleury, L., Wrachtrup, J., and von Borczyskowski, C.: Scanning confocal optical microscopy and magnetic
resonance on single defect centers, Science, 276, 2012–2014,
https://doi.org/10.1126/science.276.5321.2012, 1997. a
He, X.-F., Manson, N. B., and Fisk, P. T.: Paramagnetic resonance of
photoexcited N-V defects in diamond, I. Level anticrossing in the 3A
ground state, Phys. Rev. B, 47, 8809–8815, https://doi.org/10.1103/PhysRevB.47.8809, 1993. a
Henstra, A., Lin, T.-S., Schmidt, J., and Wenckebach, W.: High dynamic nuclear polarization at room temperature, Chem. Phys. Lett., 165, 6–10,
https://doi.org/10.1016/0009-2614(90)87002-9, 1990. a, b, c
Jelezko, F., Gaebel, T., Popa, I., Gruber, A., and Wrachtrup, J.: Observation
of Coherent Oscillations in a Single Electron Spin, Phys. Rev. Lett., 92,
076401, https://doi.org/10.1103/PhysRevLett.92.076401, 2004. a
Kagawa, A., Murokawa, Y., Takeda, K., and Kitagawa, M.: Optimization of 1H spin density for dynamic nuclear polarization using photo-excited triplet electron spins, J. Magn. Reson., 197, 9–13, https://doi.org/10.1016/j.jmr.2008.11.009, 2009. a
Kagawa, A., Negoro, M., Ohba, R., Ichijo, N., Takamine, K., Nakamura, Y.,
Murata, T., Morita, Y., and Kitagawa, M.: Dynamic Nuclear Polarization using
Photoexcited Triplet Electron Spins in Eutectic Mixtures, J. Phys. Chem. A,
122, 9670–9675, https://doi.org/10.1021/acs.jpca.8b09934, 2018. a
Kagawa, A., Miyanishi, K., Ichijo, N., Negoro, M., Nakamura, Y., Enozawa, H.,
Murata, T., Morita, Y., and Kitagawa, M.: High-field NMR with dissolution
triplet-DNP, J. Magn. Reson., 309, 106623, https://doi.org/10.1016/j.jmr.2019.106623,
2019. a, b
King, J. P., Coles, P. J., and Reimer, J. A.: Optical polarization of
13C nuclei in diamond through nitrogen vacancy centers, Phys.
Rev. B, 81, 073201, https://doi.org/10.1103/PhysRevB.81.073201, 2010. a
King, J. P., Jeong, K., Vassiliou, C. C., Shin, C. S., Page, R. H., Avalos,
C. E., Wang, H.-J., and Pines, A.: Room-temperature in situ nuclear spin
hyperpolarization from optically pumped nitrogen vacancy centres in diamond,
Nat. Commun., 6, 8965, https://doi.org/10.1038/ncomms9965, 2015. a
Köhler, J., Disselhorst, J., Donckers, M., Groenen, E., Schmidt, J., and
Moerner, W.: Magnetic resonance of a single molecular spin, Nature, 363,
242–244, https://doi.org/10.1038/363242a0, 1993. a
Lesage, A., Lelli, M., Gajan, D., Caporini, M. A., Vitzthum, V., Miéville, P., Alauzun, J., Roussey, A., Thieuleux, C., Mehdi, A., Bodenhausen, G., Copéret, C., and Emsley, L.: Surface enhanced NMR spectroscopy by dynamic nuclear polarization, J. Am. Chem. Soc., 132, 15459–15461, https://doi.org/10.1021/ja104771z, 2010. a
Loretz, M., Takahashi, H., Segawa, T. F., Boss, J. M., and Degen, C. L.:
Optical hyperpolarization of nitrogen donor spins in bulk diamond, Phys. Rev.
B, 95, 064413, https://doi.org/10.1103/PhysRevB.95.064413, 2017. a
Lowe, I. J. and Gade, S.: Density-Matrix Derivation of the Spin-Diffusion
Equation, Phys. Rev., 156, 817–825, https://doi.org/10.1103/PhysRev.156.817, 1967. a
Maly, T., Debelouchina, G. T., Bajaj, V. S., Hu, K.-N., Joo, C.-G.,
Mak-Jurkauskas, M. L., Sirigiri, J. R., van der Wel, P. C., Herzfeld, J.,
Temkin, R. J., and Griffin, R. G.: Dynamic nuclear polarization at high magnetic fields, J. Chem. Phys., 128, 052211, https://doi.org/10.1063/1.2833582, 2008. a
Mehring, M.: Principles of High Resolution NMR in Solids, Springer, Berlin, Heidelberg, Germany, 344 pp., https://doi.org/10.1007/978-3-642-68756-3, 1983. a
Mindarava, Y. L., Blinder, R., Liu, Y., Scheuer, J., Lang, J., Agafonov, V. N., Davydov, V. A., Laube, C., Knolle, W., Abel, B., Naydenov, B., and Jelezko, F.: Synthesis and coherent properties of 13C enriched sub-micron diamond particles with nitrogen vacancy color centers, Carbon, 165, 395–403, https://doi.org/10.1016/j.carbon.2020.04.071, 2020. a
Negoro, M., Nakayama, K., Tateishi, K., Kagawa, A., Takeda, K., and Kitagawa,
M.: 2H-decoupling-accelerated 1H spin diffusion in dynamic nuclear
polarization with photoexcited triplet electrons, J. Chem. Phys., 133,
154504, https://doi.org/10.1063/1.3493453, 2010. a
Negoro, M., Kagawa, A., Tateishi, K., Tanaka, Y., Yuasa, T., Takahashi, K., and Kitagawa, M.: Dissolution dynamic nuclear polarization at room temperature
using photoexcited triplet electrons, J. Phys. Chem. A, 122, 4294–4297,
https://doi.org/10.1021/acs.jpca.8b01415, 2018. a, b
Nelson, S. J., Kurhanewicz, J., Vigneron, D. B., Larson, P. E., Harzstark,
A. L., Ferrone, M., Van Criekinge, M., Chang, J. W., Bok, R., Park, I.,
Reed, G., Carvajal, L., Small, E. J., Munster, P., Weinberg, V. K., Ardenkjaer-Larsen, J. H., Chen, A. P., Hurd, R. E., Odegardstuen, L.-I., Robb, F. J., Tropp, J., and Murray, J. A.: Metabolic imaging of patients with prostate cancer using hyperpolarized [1−13C] pyruvate, Sci. Transl. Med., 5, 198ra108, https://doi.org/10.1126/scitranslmed.3006070, 2013. a
Nishimura, K., Kouno, H., Tateishi, K., Uesaka, T., Ideta, K., Kimizuka, N.,
and Yanai, N.: Triplet dynamic nuclear polarization of nanocrystals dispersed
in water at room temperature, Phys. Chem. Chem. Phys., 21, 16408–16412,
https://doi.org/10.1039/c9cp03330k, 2019. a
Nishimura, K., Kouno, H., Kawashima, Y., Orihashi, K., Fujiwara, S., Tateishi, K., Uesaka, T., Kimizuka, N., and Yanai, N.: Materials chemistry of triplet dynamic nuclear polarization, Chem. Commun., 56,
7217–7232. https://doi.org/10.1039/D0CC02258F, 2020. a
Overhauser, A. W.: Polarization of Nuclei in Metals, Phys. Rev., 92, 411–415, https://doi.org/10.1103/PhysRev.92.411, 1953. a
Parker, A. J., Jeong, K., Avalos, C. E., Hausmann, B. J., Vassiliou, C. C.,
Pines, A., and King, J. P.: Optically pumped dynamic nuclear
hyperpolarization in 13C-enriched diamond, Phys. Rev. B, 100, 041203,
https://doi.org/10.1103/PhysRevB.100.041203, 2019. a
Peng, W. K., Takeda, K., and Kitagawa, M.: A new technique for cross
polarization in solid-state NMR compatible with high spinning frequencies and
high magnetic fields, Chem. Phys. Lett., 417, 58–62,
https://doi.org/10.1016/j.cplett.2005.10.012, 2006. a
Rogers, L., Armstrong, S., Sellars, M., and Manson, N.: Infrared emission of
the NV centre in diamond: Zeeman and uniaxial stress studies, New J. Phys.,
10, 103024, https://doi.org/10.1088/1367-2630/10/10/103024, 2008. a
Scheuer, J., Schwartz, I., Chen, Q., Schulze-Sünninghausen, D., Carl, P.,
Höfer, P., Retzker, A., Sumiya, H., Isoya, J., Luy, B., Plenio, M. B., Naydenov, B., and Jelezko, F.: Optically induced dynamic nuclear spin polarisation in diamond, New J. Phys., 18,
013040, https://doi.org/10.1088/1367-2630/18/1/013040, 2016. a
Segawa, T. F. and Shames, A. I.: How to Identify, Attribute, and Quantify
Triplet Defects in Ensembles of Small Nanoparticles, J. Phys. Chem. Lett.,
11, 7438–7442, https://doi.org/10.1021/acs.jpclett.0c01922, 2020. a
Segawa, T. F., Doll, A., Pribitzer, S., and Jeschke, G.: Copper ESEEM and
HYSCORE through ultra-wideband chirp EPR spectroscopy, J. Chem. Phys., 143,
044201, https://doi.org/10.1063/1.4927088, 2015. a
Sosnovsky, D. V. and Ivanov, K. L.: Magnetic field dependence of triplet-state
ONP: theoretical analysis in terms of level anti-crossings, Mol. Phys., 117,
2740–2755, https://doi.org/10.1080/00268976.2018.1504996, 2019. a
Stehlik, D. and Vieth, H.-M.: Time evolution of electron-nuclear
cross-polarization in radiofrequency induced optical nuclear spin
polarization, in: Pulsed Magnetic Resonance: NMR, ESR, and Optics: A
Recognition of Hahn, E. L., edited by: Bagguley, D. M. S., Oxford
University Press, Oxford, UK, 446–477, 1992. a
Stoll, S. and Schweiger, A.: EasySpin, a comprehensive software package for
spectral simulation and analysis in EPR, J. Magn. Reson., 178, 42–55,
https://doi.org/10.1016/j.jmr.2005.08.013, 2006. a
Takeda, K., Takegoshi, K., and Terao, T.: Dynamic nuclear polarization by
photoexcited-triplet electron spins in polycrystalline samples, Chem. Phys.
Lett., 345, 166–170, https://doi.org/10.1016/S0009-2614(01)00840-5, 2001.
a
Tateishi, K., Negoro, M., Nishida, S., Kagawa, A., Morita, Y., and Kitagawa,
M.: Room temperature hyperpolarization of nuclear spins in bulk, P. Natl. Acad. Sci. USA, 111, 7527–7530, https://doi.org/10.1073/pnas.1315778111, 2014. a, b
Tateishi, K., Negoro, M., Nonaka, H., Kagawa, A., Sando, S., Wada, S.,
Kitagawa, M., and Uesaka, T.: Dynamic nuclear polarization with photo-excited
triplet electrons using 6,13−diphenylpentacene, Phys. Chem. Chem. Phys.,
21, 19737–19741, https://doi.org/10.1039/C9CP00977A, 2019. a
Terada, D., Segawa, T. F., Shames, A. I., Onoda, S., Ohshima, T., Osawa, E.,
Igarashi, R., and Shirakawa, M.: Monodisperse Five-Nanometer-Sized Detonation
Nanodiamonds Enriched in Nitrogen-Vacancy Centers, ACS Nano, 13, 6461–6468,
https://doi.org/10.1021/acsnano.8b09383, 2019. a
Thiering, G. and Gali, A.: Theory of the optical spin-polarization loop of the nitrogen-vacancy center in diamond, Phys. Rev. B, 98, 085207,
https://doi.org/10.1103/PhysRevB.98.085207, 2018. a
van Kesteren, H. W., Wenckebach, W. T., Schmidt, J., and Poulis, N.: Dynamic
nuclear polarization of proton spins via photoexcited triplet states: the
system phenanthrene in fluorene, Chem. Phys. Lett., 89, 67–70,
https://doi.org/10.1016/0009-2614(82)83344-7, 1982. a
van Kesteren, H. W., Wenckebach, W. T., and Schmidt, J.: Production of High,
Long-Lasting, Dynamic Proton Polarization by Way of Photoexcited Triplet
States, Phys. Rev. Lett., 55, 1642–1644, https://doi.org/10.1103/PhysRevLett.55.1642,
1985. a
Wenckebach, W. T.: Essentials of dynamic nuclear polarization, Spindrift
Publications, Burgh-Haamstede, The Netherlands, 296 pp., 2016. a
Wrachtrup, J., von Borczyskowski, C., Bernard, J., Orrit, M., and Brown, R.:
Optical detection of magnetic resonance in a single molecule, Nature, 363,
244–245, https://doi.org/10.1038/363244a0, 1993. a
Yap, Y. S., Tabuchi, Y., Negoro, M., Kagawa, A., and Kitagawa, M.: A Ku band
pulsed electron paramagnetic resonance spectrometer using an arbitrary
waveform generator for quantum control experiments at millikelvin
temperatures, Rev. Sci. Instrum., 86, 063110, https://doi.org/10.1063/1.4922791,
2015. a
Yu, H.-L., Lin, T.-S., Weissman, S., and Sloop, D. J.: Time resolved studies of pentacene triplets by electron spin echo spectroscopy, J. Chem. Phys., 80,
102–107, https://doi.org/10.1063/1.446491, 1984. a, b, c
Short summary
We show 13C spin hyperpolarization using laser irradiation at room temperature in two different systems: 1. pentacene doped in organic crystals of benzoic acid and 2. nitrogen-vacancy (NV) color centers in microdiamonds. The 13C NMR signal was enhanced by a factor of > 3000 using pentacene and > 300 using NV centers as polarization sources. We analyze the pros and cons of these two systems and discuss their prospects for room-temperature enhancement of NMR signals.
We show 13C spin hyperpolarization using laser irradiation at room temperature in two different...
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